#include <stdio.h>

int main() 
{
    int x1 = 0;
    int y1 = 0;
    int x2 = 0;
    int y2 = 0;
    scanf("%d %d\n",&x1,&y1);
    scanf("%d %d",&x2,&y2);
    printf("%d",(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
    return 0;
}